BrakTec Master Cylinder Problems - Why

Discussion in 'Trials' started by motobene, Sep 2, 2015.

  1. motobene

    motobene Motoing for 46 years

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    As the OP, I have found complete info on this problem to be coming slowly. These master cylinders are on a lot of brands. Please read the whole thread before jumping to conclusions. As with problems like this, the easy path is making POS and 'can never be trusted again' comments. The mature path is focusing on identifying the problem and the solution and moving on. Often the difference between problems and no problems in manufactured parts is very subtle.

    There is all sorts of detail farther down this thread.


    I found out today why there was a run of bad BrakTec rear master cylinders. Not sure if front master cylinder involved too (yes it is). I was talking to Stu Preston about them and he said when he was vising the factory, they showed him what the problem was. Having had problems like these in my manufacturing and design days, I had to chuckle and shake my head.

    The problem was said to be in the diameter of the fluid refresh hole. I don't have the exact details, but the early Brake Tech master cylinders was reported to have a bit too large fluid refresh hole, and when the cup seal was passing over that hole from its resting position on the way to pressurizing the brakes, apparently the seal lips would pucker back into the hole and get nipped. The fix was making that hole just a bit smaller! I found out later there was more to this than hole diameter. The edge condition of the holes where they meet the cylinder may be just as much or more important.

    AJP went kaput sometime around `11 or `12, then in a scramble to secure supply Gas Gas tapped Formula. Formula make the best forks in my opinion, but their brakes have had some problems. Then came Brake Tech, bringing back the AJP-type designs but with updates. Perhaps AJP actually became Brake Tech... I don't know. But whatever happened, a nuance of engineering was missed, and they burned themselves.

    If anyone knows more on this, please chime in.

    It's hard to make a big hole smaller in a honed and hard coated cast aluminum, but perhaps if a person was good at machining the hole could be plugged and re drilled and the bore honed? There must be a number of these bad ones out there that just need a smaller fluid refresh hole? Not the whole story - read on.
    #1
  2. Zuendapp

    Zuendapp Been here awhile

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    My riding friend has a 2014 Pro 250 and his rear master cylinder quite working within a few hours of new. He was told that it was most likely metal shavings in it and was not cleaned well in manufacturing. Yes, he tore it apart and had a pencil eraser head size of metal shavings. He chose not to rebuild, but just replace the complete master cylinder. He didn't want issues down the road.

    Terry
    #2
  3. Brewtus

    Brewtus Buffoonery, Inc.

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    Oh yeah, it happens on front cylinders as well. Seen it on a '14 Repsol a month ago. Lineaway had an AJP kit that worked in the BrokeTech cylinder.
    #3
  4. thegraydog

    thegraydog 2 wheels X 6 ways

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    'Bene, my rear braketec cylinder failed at Ute Cup 2014 on my thirty-hour GG300. Stan Hensley (colorfully!) diagnosed it at trailside. Billy Burgener fiddled with it and confirmed. Dale Malasek was there and comped me a new assembly and bled it for me, using Dot 3 from Jon Stoodley, while Gary Hoover pestered and goofed around. Howzat for name-dropping!?
    Anyway, Dale's assessment is that braketec skipped running a ball hone into the cylinder after drilling the port, leaving a little burr. Which bit the seal.

    Two weeks later my braketec clutch failed in a trials, same symptom of intermittent loss of action. Dale by email specified a ball hone for me, and with a new seal kit and a quick honing (at the lever) I have had no further issues.
    #4
  5. slicktop

    slicktop Been here awhile

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    As a side note, Grimeca has not been impressive to me.
    I would not mind having the extra weight of a Brembo.
    #5
  6. lineaway

    lineaway Long timer

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    There is a reason you see AJP brakes on the new bikes of top riders that came with another product. There for several years, you would take off the AJP`s from your old bike and swap them with your new bike.
    #6
  7. Brewtus

    Brewtus Buffoonery, Inc.

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    You know, something has been pestering me since my post this morning.

    Brake Tech took over the engineering and tooling from AJP, and started up again. Really??

    From a manufacturing point of view, this should have been a easy transition. Based on the responses here, that is not the case. Judged SOLELY on what I've read here, BT took over AJP's production and started production again. My point here is this. So where did BT differentiate from AJP's original prints? Their proven designs? Surely BT inherited the AJP engineering drawings, layouts, PDFs, DWGs, DWFs, STEPs, what have you before they started production. Did some "genius" at BT decided on their own to modify the original proven and standard design on their own, or did someone not pay close attention to the Final Production Revision? Too big a hole? Big oversight in Engineering (if there is any at BT) or no Final Production Review before release. The reports of metal shavings in released products? Don't get me started on the QC department's obvious and glaring failings (if there truly is a QC department at BT). In this day and age, these shortcomings are beyond unacceptable. Engineering and Manufacturing moved well past this point in the 1950's.

    Finish hone a master cylinder on a new bike?

    Metal shavings in the same cylinders??

    Glaring engineering defect in the same cylinders???

    Would any of you put up with this shit on your new Toyota? Your new Dodge? Ford? Duramax? Any other form of transportation you purchase new???

    Of course not. Why put up with it on your new Trials bike?

    Crap. Might as well be Chinese. :flip
    #7
  8. DerViking

    DerViking Shred

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    I give that rant 7 out of 10. Not bad.

    And fair points. I was amazed at the piss poor final assembly quality of my 07 Gas Gas. It's proven a good machine but... And jeaus, hydraulic master/slave is pretty well proven tech. How did they screw it up so completely and widely. I guess it speaks to a small market with too little competition.
    #8
  9. motobene

    motobene Motoing for 46 years

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    Well open me a Pandora's box! Shavings and lack of hone, etc. Stu made it sound like the problem was ONE , discovered, then taken care of. Maybe it was or they were, and we are looking at lack of a recall so problematic stuff stayed in inventory. Well I hope that is - was it.

    I've now got BrakeTec on my latest bike, which will of course be yet another individual to get to know. I ended up having the problem (read on), but also found out BrakeTec is better designed and in most details manufactured higher quality than AJP. Too bad they blew it in some small details and caused a lot of people problems.

    In my manufacturing experience I found people who were smart in practical things and worked liked they owned a place could produce great product, even in a junky shop with poor controls. They were the controls. I have lived through the burdens of many quality system convulsions with various acronyms. That stuff makes sense, but people with those systems who are mediocre or are pissed at the management can make poor product. If a company is big enough and has been at it long enough, the systems become so intricate they can be much more plug and play with people, but even then one doofus can still mess things up.

    Great manufacturing is far more than moving tooling and following prints. Parts and assembly drawings give specs only, but do not address how to manufacture something. Small outfits sometimes entirely lack documented processes. The how will reside in a few good people that tend not to document things because in the craftsman mentality, job security is seen as holding such details close to the chest. In start-up efforts, if you see great product in year one it is almost a miracle, there are a few fantastic people involved. There is just so much to learn that is not easily documented.

    When a business crashes the financial types are too often clueless as to who is critical or who is not, really. Sometimes the best people are a pain in the ass and get swept out.

    All things are self correcting, however, either within the lifetime of one company, or it will take them under. Again, my view has changed. Good stuff with some stupid little flaws.
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  10. thegraydog

    thegraydog 2 wheels X 6 ways

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    I have begun to wonder why we think this. Has a smart phone ever been manufactured anywhere but China?
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  11. mung

    mung Been here awhile

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    12 300 Raga. Went through one rear brake mc, one clutch mc and four front brake mc's before I got stuff that lasted more than 10 minutes. Every one had a large burr at the tiny bleed hole. Worked perfect since.
    #11
  12. motomofo

    motomofo Been here awhile

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    The master cylinders on those bikes were a nightmare! I didn't own a GG at that point, but felt sorry for all my buddies who did. The Braketec components on my '13 Factory have worked flawlessly, thank goodness.
    #12
  13. Brewtus

    Brewtus Buffoonery, Inc.

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    Ah yes, the meat factor. Good points that I did not bring up in my previous rant. I'm very sorry to say that I know all too well how a disgruntled and lackadaisical staff can affect the outcome of manufactured goods. The business that I currently occupy space at has monumental potential, but is hamstrung by greed and incompetence at the top level. On top of that they treat their staff rather poorly, which greatly affects quality. It's a shame, because the place truly does have the potential for greatness. For their sake and the sake of their employees, I truly hope that the daily BS drama that grinds on at my current workplace is not occurring at Brake Tech.

    Don't get me wrong, I'm glad that BT stepped up to the plate and took over AJP's production. If they are going to stay in the game they might want to get into their big boy pants if they want to play with the likes of Nissin and Brembo though.

    BTW, does anyone know exactly why AJP went under? :dunno
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  14. Zuendapp

    Zuendapp Been here awhile

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    2014 Martin Matejicek's GasGas 300 that he road in the USA Nationals appeared to have the larger AJP clutch master cylinder and a remote reservoir rear master cylinder. The front brake master cylinder was a Nissin???
    Does anyone know more info on why he used this setup?

    Terry


    #14
  15. lineaway

    lineaway Long timer

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    Why, the clutch would work better and same with the front brake. I bet he had an AJP or some Honda rear brake m/c. All three also were so he would not have a failure. The new rear brake m/c`s are junk.
    #15
  16. motobene

    motobene Motoing for 46 years

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    We'll see how long my junk lasts.
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  17. motobene

    motobene Motoing for 46 years

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    Got some great update info from Dale Malasec.

    He said the BrakTec problem has been wide spread, and cited one example of a Sherco national rider in 2014 having all three cup seals fail in an event causing DNF.

    The symptom of the problem is sustained lever pull with levers and pedals slowly bottoming. The cause apparently lies in the edge condition of the refresh hole in the reservoir, as in a sharp edge or sharp edge plus a burr.

    I asked him if the problem was bigger on the rear brake master cylinder and he said that no, in his experience it has been more common on the handlebar master cylinders.

    I asked him about the typical time to cup seal leaking and he said it often happens within a few hours on a new bike, so I suppose if you pass the 10-hour mark, maybe it won't be a problem? In that case if one is not sure, the following fix could be done as prophylaxis (prevention) to reduce the probability of a nipped cup seal.

    The fix, as explained by Dale:

    Once a master cylinder fails, it will be necessary to have a re build kit, as individual cups seals aren't available at present.

    He lays the bike on one side and removes the lever and piston circlip. Out comes the piston assembly. He then runs a 9.5mm = 3/8" flexible cylinder (ball) hone turning at moderate speed, in and then back out of the bore, one time. Something like this:

    http://www.enginehones.com/95m120sc.html

    This is not the right hone, at least so far I don't think so (still working on it). Get the 320-grit diamond version of the hone.

    Stu Preston at Jack's Cycles has used these and knows where to get them. I'm unsure about the grit, so it might be good to check with him first. I checked McMaster Carr and they have no 3/8" hone and in metric, not 9.5mm Odd. For reference purposes you can see various grits on their page, however:

    http://www.mcmaster.com/#ball-hones/=yt4hng

    He then flushes the bore and inserts a new piston assembly then bleeds the system. He says once the fix is done the problem has not repeated.

    This means the hole diameter is not so much the issue as is the edge condition of the hole. A smaller hole will make edge condition issue less sensitive, but I'm not so sure a slight difference in diameter will make much difference. Maybe that was the speculation before there was a full understanding of a problem? It's hard to see details inside the bores of black parts, even under a microscope.

    The master cylinders are typically hard coated for wear resistance, so a silicone carbide or aluminum oxide ball hone will barely scratch the bore, but it will microscopically round off and clean up a presented hole edge... and that is the point of the fix.

    This less scratching of the bore while knocking hole edges down may or may not be a good thing, I don't know just yet. I've got the diamond hone because it is supposed to be for ceramics, and hard coat is a ceramic.

    Once leaking, it presently requires a master cylinder rebuild kit to fix each leaking master cylinder with a new cup seal. Dale said he was going to Spain soon and will visit Brake Tech and ask for a bag of those seals given it's only the cup seal that gets damaged. As tool may be required for cup seal install given the dinky root diameter of the piston. I've machined one before... a bullet shaped thing that allows the seal to expand and drop into the groove. I'm not sure if it possible to install a cup seal without a too. Maybe possible but not easy.

    Still checking on availability of cup seals only. Yes, for sure they do get nipped, and no, you don't need the piston replaced. Much will depend on availability of cup seals and whether my tool to help get the dinky things over the lip on the piston with damaging them will work very effectively.
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  18. DerViking

    DerViking Shred

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    I have on an Ajp. I had a new piston, which turned out to be too big for the bore. I was able to remove the cup seal with an o ring pick, then evenly sand down the piston with emery paper. I know the machinists here are cringing. Putting the seal back on by the same method ended up tearing it. The old seal salvaged from my 2000 was a little looser, and I was able to gradually work it on using a straight scribe tool. Still working fine 3 years later, knock on wood. ..
    #18
  19. motobene

    motobene Motoing for 46 years

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    Nice work, DerViking. That job takes much patience.

    The problem with fitting new cups is the very small bore diameter. In the older days master cylinder diameters were bigger (I recall my Fantic had a 11mm front brake master cylinder? Or something did. With an external cup diameter only 9.5mm, and the necessarily thick cup seal, the waist diameter on the piston is like a very skinny 19th-century woman with a corset tightened to the spine!
    #19
  20. 2whlrcr

    2whlrcr gooligan

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    Hey 'bene....

    That's nice looking Fantic. Glad I don't have the room.
    #20
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